1. Field of the Invention
The present invention relates to a tool and a method for coating an interior surface of an elongated pipe member. More particularly, the present invention pertains to a tool and a method for coating an interior surface of an elongated pipe member using a plug member.
2. Description of the Prior Art
It has been desired to coat an interior surface of a pipe member for use in a heat exchanger for the purpose of preventing corrosion and improving heat exchange efficiency. However, such coating is not easy in view of the fact that the pipe members to be used in a heat exchanger are generally large in length and curved in an complicated configuration.
It has been known to use a plug member for removing scales and slugs on an interior surface of an elongated pipe member. The Japanese patent publication Sho 58-36634 discloses such technology. According the teachings of the Japanese patent publication, the plug member is made of a resilient cylindrical body with or without metallic pins projecting from the outer surface of the body. The plug member is slidably fitted to the pipe member and progressed in the member under a thrust force provided by a hydraulic pressure applied behind the plug member.
It may be possible to apply the known method of removing scales and slugs in a pipe member to a process for coating the interior surface of an elongated pipe member. For example, the plug member may be connected with a tube for continuously supplying the outside surface of the plug member with a coating material while the plug member is being progressed longitudinally in the pipe member. This method of coating the interior surface of the pipe member may not be satisfactory because it may be difficult to obtain a coating of uniform thickness. The problem will be significant in the case of a curved pipe members.